In recent years, flat panel displays have been widely used in various commodities and fields, and the flat panel displays are required to have a larger size, a higher image quality, and a lower power consumption.
Under these circumstances, an organic EL display device is attracting considerable attention as an all-solid-state flat panel display with excellent low-voltage driving capability, high-speed responsibility, and self-luminous property. The organic EL display device includes an organic EL element that utilizes the electroluminescence of an organic material.
In an active matrix type organic EL display device, e.g., a thin-film organic EL element is provided on a substrate having TFTs (thin-film transistors). The organic EL element includes an organic EL layer (including a light emitting layer) that is disposed between a pair of electrodes. The TFTs are connected to one of the pair of electrodes. A voltage is applied across the pair of electrodes so that the light emitting layer emits light, thereby displaying images.
In the above conventional organic EL display device, it has been proposed that the organic EL element is sealed to protect it from degradation due to moisture or oxygen.
Specifically, the conventional organic EL display device includes an organic EL element, a substrate that is provided with the organic EL element, and an encapsulating substrate that is located opposite the substrate (see, e.g., Patent Document 1). In this organic EL display device, the organic EL element can be sealed by forming a frame-shaped glass frit between the substrate and the encapsulating substrate so as to surround the organic EL element.